Anchor system for pre-insulated piping

ABSTRACT

An anchor system is shown for use with a pre-insulated piping system having an inner steel carrier pipe surrounded by a layer of insulation and then by an outer protective jacket. The anchor system includes an inner carrier pipe for insertion within the length of the piping system at a selected point. A steel anchor sleeve surrounds a portion of the length of carrier pipe and insulation. It terminates at one end at an outwardly flaring anchor plate which is subsequently embedded within a concrete anchor block. A steel end cap is welded to a second, opposite end of the sleeve and to the inner carrier pipe at a point along the length of piping which is outside the concrete anchor block and which is spaced apart from the location of the anchor plate, whereby heat from the high temperature fluids in the piping is transferred to the end cap at a location along the length of piping which is distant from the location of the anchor plate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/701,152, filed Feb. 5, 2010, entitled “Anchor System ForPre-Insulated Piping,” which was, in turn, a continuation-in-part ofearlier filed U.S. patent application Ser. No. 12/456,664, filed Jun.19, 2009, entitled “Anchor System For Pre-Insulated Piping,” by the sameinventor, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to pre-insulated piping systems of thetype used to convey high temperature fluids and to an improved anchorinstallation for such systems for anchoring a section of pre-insulatedpiping to prevent undesired movement thereof.

2. Description of the Prior Art

There are many instances in which insulated pipelines are needed. Forexample, distributed HVAC (heating, ventilation and air conditioning)applications utilize chilled water for cooling and steam for heating.The chiller and boiler are typically contained in a central location andthe chilled water and steam are distributed to other locations. Forexample, on a school or college campus, the chiller and boiler may belocated in a power plant building. The chilled water and steam aredistributed to classrooms in separate buildings.

A set of insulated pipelines is used to convey the chilled water fromthe chiller to other locations and back to the chiller. Another set ofinsulated pipelines is used to carry the steam from the boiler to theother locations and back to the boiler. The insulated pipelines areusually located underground.

Pre-insulated pipe is conventional and commercially available. There arepredominately two types of such piping systems in use: Class-A drainabledryable testable (DDT); and polyurethane or polyisocyanurate “bonded”foam systems. Both of these systems use an inner carrier pipe to conveyfluid. Although steel is commonly used for the inner pipe which carriesthe media to be piped, copper or aluminum or other metals as well asfiberglass, PVC, and similar materials may be utilized, as well. Aroundthe outside of the steel pipe is a layer of insulating foam such as, forexample, polyisocyanurate foam. Around the outside of the foam is ajacket of hard thermoplastic (such as high density polyethylene, HDPE).The foam has set up or cured within the outer jacket so as to bond tothe jacket and to the inner pipe. The plastic jacket protects the foamfrom mechanical damage and also provides a water tight seal to preventcorrosion of the steel pipe. In the bonded type system, the foam andouter jacket do not move relative to the inner pipe. In the Class-A typesystem, on the other hand, the insulated inner pipe is designed to moveindependently of the associated outer jacket. In fact, there is an airgap between the inner pipe and outer carrier pipe in the class-A typesystem.

There are various examples in the prior art of the need for “anchoring”such pre-insulated piping systems, either to guard against earthmovement or to counteract thermal stresses in the pipe line itself.Also, anchors are generally needed at the entry ports of piping into,for instance, a concrete wall. The concrete wall might be a structuralwall or foundation wall of a residential, commercial or industrialbuilding or structure. Another common example is in the area of concretemanholes, valve pits and the like, in which conduits enter and leave themanhole through a sealed “porthole” or point of entry of the conduitinto a sidewall or riser section of the manhole. It is generallynecessary to anchor the pre-insulated pipeline at a point just prior toentry into the manhole since the sealed porthole does not generallyallow for longitudinal movement of the piping.

Despite the advances which have been made in pre-insulated pipingsystems in recent years, and in particular to anchor points in suchsystems, a need continues to exist for further improvements.

For example, a need exists to better accommodate the high temperatureswhich are presently experienced at the location of the steel anchorplate which is used in such anchor assemblies, where the anchor platecontacts the steel carrier pipe and also contacts the surrounding foaminsulation, particularly where the steel carrier pipe is carrying hightemperature fluids.

Reducing the excess heat present at the anchor point would also prolongthe life and increase the effectiveness of the corrosion protectivecoatings which are conventionally applied to the anchor plate and othermetal components of the system.

A need also exists for such an anchor system which utilizes many of theconventionally available materials and manufacturing techniques commonlyused in the industry and which is relatively simple in design andeconomical to implement.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide amechanism for better accommodating the high temperatures which arepresently experienced at the location of the steel anchor plate which isused in such anchor assemblies of the type described, where the anchorplate contacts the steel carrier pipe and also contacts the surroundingfoam insulation, particularly where the steel carrier pipe is carryinghigh temperature fluids.

By providing a mechanism for controlling the heat transfer which occursat the steel anchor plate, the life and effectiveness of conventionalcorrosion coatings for the metal surfaces employed will be extended andimproved. It is also possible that less exotic, more economicalcorrosion coatings can be effectively employed.

Accordingly the present invention has as its object to provide animproved anchor installation for a pre-insulated piping system of thetype used for conveying high temperature fluids. The particular type ofpiping system under consideration includes lengths of insulated andjacketed pre-insulated piping. In one form of the invention, theimproved anchor installation is applied to a bonded foam pre-insulatedpiping system; i.e., the piping is made up of an inner carrier pipehaving an interior surface and an exterior surface with an envelope offoamed insulation surrounding the inner pipe exterior surface. An outerprotective jacket surrounds the envelope of insulation. The length ofpiping has a joining end for joining to an adjacent length of piping,whereby the adjacent lengths of piping provide a continuous length offluid conduit for conveying high temperature fluids.

In the bonded foam system, the anchor installation of the invention islocated at a selected point along the length of the piping system andincludes an inner metal carrier pipe for joining to the joining end ofan adjacent length of bonded foam piping in the piping system. Thecarrier pipe is surrounded by an envelope of foamed insulation. Aspecial metal anchor sleeve surrounds at least a portion of the lengthof carrier pipe and foamed insulation. The anchor sleeve has acylindrical length which terminates at a first end at an outwardlyflaring anchor plate which is subsequently embedded within a concreteanchor block. The sleeve also has an opposite, second end. The sleeve isarranged to surround the envelope of foamed insulation in spaced apartrelationship to the inner carrier pipe and extend outwardly from theconcrete anchor block along the length of piping for a predetermineddistance.

A metal end cap, or other closure device, joins the anchor sleeve at thesecond end thereof to the inner carrier pipe at a point along the lengthof piping which is outside the concrete anchor block and which is spacedapart from the location of the anchor plate, whereby heat from the hightemperature fluids in the piping is transferred to the end cap at alocation along the length of piping which is distant from the locationof the anchor plate.

The inner carrier pipe of the anchor installation has an opposite endwhich extends from the anchor block in an opposite direction from theanchor sleeve. The opposite end of the carrier pipe is surrounded by alayer of foam insulation and then by an outer protective jacket. In onepreferred form of the anchor assembly of the invention, the outerprotective jacket is, in turn, surrounded along a portion of the lengththereof by a watershed ring which is joined to the anchor plate at oneextent and which is joined to the outer protective jacket at an oppositeextent. In one preferred form, the watershed ring is formed of metal andthe outer protective jacket is formed of a synthetic polyolefinmaterial, the watershed ring being joined to the outer protective jacketby a watertight sleeve of heat shrink material.

Preferably, the foam insulation is selected from the group consisting ofpolyurethane foams and high temperature polyisocyanurate foams. Theouter protective jacket is preferably a synthetic polyoelfin, such asHDPE. The lengths of insulated piping can be part of a pipelineconveying steam, hot water or other hot fluids at a temperature aboveabout 212° F.

While the preferred form of the invention has been described withrespect to a bonded foam pre-insulated piping system, the principlesthereof can also be applied to a drainable, dryable, testable (DDT)system. While such systems generally feature different types ofsurrounding insulating materials and an air space between the innercarrier pipe and an outer metal conduit, the same type of metal end capcan be used to join the anchor sleeve at a second end thereof to theinner carrier pipe at a point along the length of piping which isoutside the concrete anchor block and which is spaced apart from thelocation of the anchor plate. In this way, heat from the hightemperature fluids in the carrier piping is again transferred to the endcap at a location along the length of piping which is distant from thelocation of the anchor plate.

Additional objects, features and advantages will be apparent in thewritten description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified representation of a typical distributed HVACsystem of the type under consideration which might utilize a hightemperature fluid, such as steam, for heating.

FIG. 2 is a simplified view of an anchor installation of the presentinvention in a typical arrangement where the pipeline enters anunderground valve pit.

FIG. 3 is a partial sectional view of a typical prior art anchorinstallation of the type under consideration.

FIG. 4 is a view similar to FIG. 3, but showing the improved anchorinstallation of the invention.

FIG. 5 is another view of an anchor installation similar to FIG. 4 butoverlaid with a graph which shows the temperature rise profile along thelength of the outer cylindrical sleeve with the anchor plate locationbeing at zero inches.

FIG. 6 is a view of another form of the invention, similar to FIG. 3,but showing an in-line anchor, rather than an anchor which is used at atermination point entering a structure.

FIG. 7 is a view of another form of the invention in which the anchorinstallation is applied to a drainable, dryable, testable pre-insulatedpiping system.

DETAILED DESCRIPTION OF THE INVENTION

The preferred version of the invention presented in the followingwritten description and the various features and advantageous detailsthereof are explained more fully with reference to the non-limitingexamples included in the accompanying drawings and as detailed in thedescription which follows. Descriptions of well-known components andprocesses and manufacturing techniques are omitted so as to notunnecessarily obscure the principle features of the invention asdescribed herein. The examples used in the description which follows areintended merely to facilitate an understanding of ways in which theinvention may be practiced and to further enable those skilled in theart to practice the invention. Accordingly, the examples should not beconstrued as limiting the scope of the claimed invention.

Turning first to FIGS. 1-2, there is illustrated a typical environmentin which the pre-insulated piping systems of the invention might beemployed. FIG. 1 shows a school campus having a number of isolatedbuildings 3, 5 connected by an underground insulated pipeline carryingsteam which at points includes right angle loops or elbows 9. The loops9 are provided in a typical piping system of the type illustrated inorder to compensate for expansion and contraction forces which areexerted on the piping. The piping system will also typically include oneor more manholes or “valve pits” 7. The valve pits 7 are typicallyformed of cast concrete and include portholes (10 in FIG. 2) and risersections 12.

As will be appreciated by those skilled in the art, the anchor systemsof the invention could be used with a variety of types of pipes and pipeinstallations. For sake of illustration, the principles of the inventionwill first be described in relation to a concrete valve pit used in a“bonded foam” type insulated steam piping system. FIG. 2 is a somewhatsimplified view of a portion of such an underground piping system of thetype under consideration in which pipe sections 11 and 13 are located ingenerally parallel underground plane and which are intended to intersectpreviously located manhole or valve pit 7. The pipe sections 11, 13 arefoam bonded pre-insulated piping sections, as that term is used in therelevant art. Each length of pipe includes an inner pipe, typicallyformed of steel, an envelope of foamed insulation surrounding the innerpipe, and outer protective jacket surrounding the envelope ofinsulation. The joining ends of the adjacent steel inner carrier pipeare affixed, as by being welded together, to form fixed joints, wherebythe adjacent pipe lengths provide a continuous fluid conduit forconveying high temperature fluids. The inner foamed insulation willtypically be of polyurethane or high temperature polyisocyanurate, whilethe outer protective jacket is typically formed of high densitypolyethylene (HDPE) or a similar polyolefin type material. The followingreferences, among others, teach the manufacture of prior art insulatedpiping systems of the general type under consideration: U.S. Pat. No.3,793,4111; U.S. Pat. No. 4,084,842; and U.S. Pat. No. 4,221,405, all toStonitsch et al.

The piping systems of the type illustrated in the drawings are typicallyutilized to convey fluids at high temperature and/or pressures. Forexample, a typical steam line might be conveying fluid at, for example,320° F. The temperature differentials which exists between the pipingsystem materials and the fluid being conveyed cause expansion andcontraction forces to be applied along the coaxially aligned pipelengths.

The expansion and contraction forces are partially compensated for inthe prior art by including one or more expansion loops (illustrated at 9in FIG. 1). However, it is also typically necessary to include one ormore anchor installations (such as anchor installation 15 in FIG. 2) atvarious points along the length of piping. For example, it is typicallynecessary to install an anchor assembly just prior to the portholeopenings (such as the porthole opening 10 in FIG. 2) of the concretemanhole, since the sealed portholes do not generally allow forlongitudinal movement of the piping. This is primarily due to the factthat the piping is sealed at the point of entry into the manhole orvalve pit.

For example, a Century Line Sleeve® can be cast into the wall of theconcrete manhole at the porthole location. This commercially availableproduct is a generally cylindrical sleeve formed of a polyolefinmaterial, such as high density polyethylene, which lines the porthole inthe wall of the concrete valve pit or manhole and which receives thesection of the piping entering the interior of the manhole. A Link-Seal®is one type of sealing system is then used to form the seal between thepiping and the Line Sleeve®. Both items are commercially available fromThunderline/Link-Seal of Houston, Tex. The Link-Seal® is a modular,mechanical type of seal, consisting of inter-locking synthetic rubberlinks shaped to continuously fill the annular space between the pipe andthe wall opening containing the Line Sleeve®. The presence of these andother similar types of seal assemblies generally make it necessary touse a cast concrete anchor assembly in front of the porthole entry intothe manhole or valve pit.

FIG. 3 is a partial cross-sectional view of a prior art anchor assemblyof the type under consideration which is shown being used with thebonded foam type pre-insulated piping system. The anchor system is usedwith a length of insulated and jacketed pre-insulated piping of the typehaving an inner carrier pipe 17 (shown broken away in FIG. 3) typicallyformed of a suitable metal, such as steel, and having an interiorsurface and an exterior surface. An envelope of foamed insulation 19surrounds the inner pipe exterior surface and may comprise, for examplethe previously described high temperature polyisocyanurate. An outerprotective jacket 21 surrounds the envelope of insulation. The outerprotective jacket may be an HPDE material. The length of piping has ajoining end 23 for joining to an adjacent length of piping, whereby theadjacent lengths of piping provide a continuous length of fluid conduitfor conveying high temperature fluids.

Prior art pipe lengths of this general type are commercially availableas standard factory type product. For example, such product is availablefrom Thermacor Process, LP of Fort Worth, Tex., assignee of the presentinvention. One typical example is sold commercially as the “HT-406 HighTemp Steel Piping System™.”

As will be appreciated, in the discussion which follows, the improvedanchor systems of the invention can be used advantageously with thebonded foam “HT-406 High Temp Steel Piping System™” of the typeillustrated. However, as will be described in greater detail, the anchorsystems of the invention might also be used with other commercial pipingsystems used in the insulated pipe industries, as well. For example, thesystem of the invention could be used with Applicant's “Duo-Therm 505”™system, or similar systems. In other words, the unique aspects ofApplicant's systems may be used in a variety of applications requiringanchor installations. For example, the systems of the invention offerparticular utility in situations where the insulated pipelines aresubject to expansion and contraction forces which must be controlled atthe point of entry into the building or structural sidewall orsubterranean structure such as a valve pit or manhole.

The reference in the first part of this discussion to pipe “lengths” isintended to refer to standard available factory pre-insulated piping ofthe type previously described having an inner metal pipe surrounded byan envelope of foamed insulation, which in turn, is contained within apolyolefin jacket. As referred to briefly above, typical commercialpractice involves the use of steel, copper, aluminum or alloy conveyingpipes, open or closed cell polyurethane, polyisocyanurate, polystyreneor the like, foamed rigid insulation and polypropylene, polybutylene,polyethylene, polyvinylchloride and similar protective jackets.

The term “high temperature”, as used in this discussion, will be anytemperature exceeding 250° F., which is the present temperaturelimitation at which polyurethane foam is used in bonded foam systems.Temperatures above 250° F. require the use of higher temperature foams,such as polyisocyanurate foam.

With reference again to the prior art anchor assembly shown in FIG. 3 ofthe drawings, it will be seen that the anchor assembly has an exposedjoining end which includes a steel inner carrier pipe 25 surrounded by alayer of foam insulation 27, which is in turn surrounded by an outerprotective jacket 29. An anchor plate 31 in the form of a radiallyoutwardly extending disk is welded to the steel inner carrier pipe at acentral location. The anchor plate will also typically be formed ofsteel. A steel ring 33 is welded to the anchor plate. A heat shrink tape(not shown) is typically applied over the steel ring 33 in order to sealthe ring to the HDPE jacket 29. The piping with its associated anchorplate and ring are embedded in a block of cast concrete 35 provided bythe contractor. In the particular installation shown in FIG. 3, theopposite end of the carrier pipe is closed off with a steel end cap 37and a layer of heat shrink material 39 joins the end cap 37 to the HDPEjacket 29.

While anchor installations such as the one shown in FIG. 3 have beenused commercially for many years, it will be appreciated that the directconnection between the anchor plate 31 and the inner steel carrier pipecreates a point of direct heat transfer for the high temperature fluidsbeing carried by the inner carrier pipe. As a result, an undesirable“hot point” may be created. This excessive heat can, in some instances,put a strain upon the corrosion coating which is conventionally appliedto the anchor plate. The conventionally used corrosion protectioncoatings include, for example, fusion bonded epoxy, the various urethanecoatings, etc.

It would thus be advantageous to make the anchor point “cooler” so thatthe corrosion protection coatings which are applied to the metalcomponents of the system would work as intended and for an extendedperiod of time. In the past, the available corrosion protection coatingshave degraded or failed when exposed to, for example, 220 to 300° F.temperatures and a wet environment, as where the pipeline outerprotective jacket has been breached and water contacting the innercarrier pipe starts to boil.

FIG. 4 illustrates one form of the improved anchor installation of theinvention. The anchor system of FIG. 4 is shown as being used with abonded foam, pre-insulated piping system of the type used for conveyinghigh temperature fluids, such as that which has previously beendescribed with respect to FIG. 3. In other words, the anchor assemblywill be joined to a length of insulated and jacketed pre-insulatedpiping, where the piping has the components 17-23 previously describedin FIG. 3.

The anchor installation of the invention is located at a selected pointalong the length of the piping system. The anchor installation(designated 41 in FIG. 4) includes an inner carrier pipe 43 for joiningto the joining end of an adjacent length of piping in the piping system.The carrier pipe is surrounded by an envelope of foamed insulation 45.However, in the case of the anchor assembly of FIG. 4, the foaminsulation has a special steel anchor sleeve 47 which surrounds at leasta portion of the length of carrier pipe and foamed insulation andextends longitudinally down the horizontal pipe axis. The anchor sleeveis comprised of a generally cylindrical steel conduit having acylindrical length which terminates at a first end at an outwardlyflaring anchor plate 49. The anchor plate 49 forms an outwardlyextending flange surface with respect to the remainder of the exteriorsurface of the anchor sleeve 47. The anchor sleeve 47 also has anopposite, second end 51 which terminates in a steel end plate 53 whichis welded to the inner carrier pipe 43 at a point distant from theanchor plate 49.

As will be appreciated from FIG. 4, the anchor sleeve 47 is arranged tosurround the envelope of foamed insulation 45 in spaced apartrelationship to the inner carrier pipe 43. In other words, the interiorof the cylindrical length of the sleeve 47, as well as the terminatinganchor plate 49 are spaced apart from the inner carrier pipe 43 along amajority of the length thereof, so that no heat transfer takes place inthe vicinity of the anchor plate 49. Any tendency for heat to betransferred by contact with the hot inner carrier pipe 43 would bedisplaced down the length of the sleeve 47 in the vicinity of the endplate 53 and out of the region of the concrete block 55 and anchor plate49.

In other words, the second or distal end 51 of the sleeve 47 is closedoff by means of the steel end cap 53 or other convenient fixture whichis welded onto the carrier pipe 43 at the opposite end of the anchorsleeve 47 from the anchor plate 49. The end cap thus joins the anchorsleeve 47 at the second end 51 thereof to the inner carrier pipe 43 at apoint along the length of piping which is outside the subsequentlypoured concrete anchor block 55 and which is spaced apart from thelocation of the anchor plate 49. In this way, heat from the hightemperature fluids in the piping is transferred to the end cap 53 at alocation along the length of piping which is distant from the locationof the anchor plate 49. The end cap 53, in effect, forms a sort of “heatsink” for the anchor assembly.

With reference briefly to FIG. 5 of the drawings, an anchor assembly ofthe invention, similar to the one shown in FIG. 4 but turned in theopposite direction, is overlaid with a graph showing the temperatureprofile and consequent heat rise along the outer cylindrical metalsleeve 47 with the anchor plate 49 being at zero inches. As will beapparent from the accompanying graph, the temperature profile graduallyincreases as the distance from the anchor plate 49 increases along theouter metal sleeve 47. The temperature within about 26 inches of theanchor plate 49 is below about 150° F. At 56 inches from the anchorplate, the temperature is beginning to approach 350° F. The relatively“cooler” temperatures which are experienced at the location of theanchor plate 49 serve to protect the corrosion protective coatingsutilized in the vicinity of the anchor plate.

Referring again to FIG. 4, the carrier pipe 43 has an opposite end 57which extends from the concrete anchor block 55 in an opposite directionfrom anchor sleeve 47. The opposite end 57 of the carrier pipe issurrounded by a layer of the foam insulation 45, and then by an outerprotective jacket 59 which extends from the anchor plate 49 outwardlyfrom the concrete block and parallel to the inner carrier pipe. Theouter protective jacket is, in turn, surrounded by a metal watershedring 61 which is welded at one extent to the anchor plate 49. In orderto provide a water proof enclosure, a layer of heat shrink material 62is used to provide a water proof seal between the watershed ring 61 andthe HDPE outer protective jacket 59. The “heat sink” provided by theimproved anchor sleeve assembly of the invention offers added protectionfor both the corrosion protective coating which is conventionallyapplied to the anchor plate.

A method is also shown for installing an anchor in a section ofpre-insulated piping of the type previously described. A first andsecond lengths of insulated and jacketed piping are provided, eachhaving a joining end to be joined to an end of the other length, eachpipe length comprising an inner metal pipe having an interior surfaceand an exterior surface. An envelope of foamed insulation is applied sothat it surrounds the inner pipes exterior surface and envelopes theinner pipes. Thereafter, an outer protective jacket is applied whichsurrounds the envelope of insulation. The joining ends of adjacent pipelengths are welded together to form fixed joints which are alsosurrounded by foam insulation and an outer protective jacket, wherebythe adjacent pipe lengths provide a continuous insulated fluid conduitfor conveying high temperature fluids.

The anchor assembly of the invention is installed at a selected locationwithin the length of the piping system. The anchor assembly has an innercarrier pipe for joining with ends of adjacent pipe lengths in thelength of piping. The assembly includes an inner carrier pipe forjoining to the joining end of an adjacent length of piping in the pipingsystem, the carrier pipe being surrounded by an envelope of foamedinsulation. The previously described special metal anchor sleeve is usedto surround at least a portion of the length of carrier pipe and foamedinsulation, where the metal anchor sleeve has a cylindrical length whichterminates at a first end at an outwardly flaring anchor plate which issubsequently embedded within a concrete anchor block. The anchor sleeveis arranged to surround the envelope of foamed insulation in spacedapart relationship to the inner carrier pipe and extend outwardly fromthe concrete anchor block along the length of piping for a predetermineddistance.

As previously described, a metal end cap is then used to join the anchorsleeve at the second, distal end thereof to the inner carrier pipe at apoint along the length of piping which is outside the concrete anchorblock and which is spaced apart from the location of the anchor plate,whereby heat from the high temperature fluids in the piping istransferred to the end cap at a location along the length of pipingwhich is distant from the location of the anchor plate.

FIG. 6 shows another form of the invention, similar to the installationof FIG. 4, except that an “in-line” anchor installation is shown. Inother words, the anchor installation in FIG. 7 is present in a sectionof the normal pipe run, rather than at the termination point at whichthe pipe enters a building, a wall, a valve pit, or the like. Theinstallation of FIG. 6 includes the previously described inner metalcarrier pipe 43 which is surrounded by a layer of foam insulation 45,the foam insulation 45 being surrounded by an HDPE jacket 59. As shownin FIG. 6, the anchor plate 101, coated with a high temperaturecorrosion protection coating, is welded to a water shed ring 105. Thesteel ring 105 is welded continuously to the steel anchor plate 101 andcorrosion coated on both sides.

Heat shrink material 107 circumscribes the exposed exterior of the watershed ring 105 and anchor plate 101 and is fusion bonded to the outerHDPE jacket 59. These components of the assembly are conventional.However, as shown in FIG. 6, the anchor plate 101 is now provided withthe same type of cylindrical metal sleeve 110 which passeslongitudinally down the pipeline through the layer of foam 45 to a pointdistant from the anchor 101, where it is again welded to the inner steelcarrier pipe by means of metal end cap 113, as has previously beendescribed.

FIG. 7 describes another type of pre-insulated piping system which canutilize the improved anchor installation of the invention. Withreference to FIG. 7, a drainable, dryable, testable (DDT) type system isshown having the improved anchor installation of the invention. Thesystem again features an inner metal carrier pipe 63 surrounded by alayer of insulating material 65. The insulation in this case mighttypically be high temperature rated mineral wool. Other insulatingmaterials include foam glass, fiber-glass or calcium silicate. There isthen an air gap, illustrated as 67 in FIG. 7, between the exterior ofthe inner carrier pipe 63 and an intermediate cylindrical metal conduit69.

The spacing of the carrier pipe relative to the intermediate conduit maybe maintained by one or more spacer elements (not shown) located alongthe length of the piping between the two elements. The intermediatemetal conduit 69 is welded to the anchor plate 71 which is againembedded in a concrete block which is poured by the contractor.

As previously described with respect to the bonded foam system, theanchor plate 71 is not directly welded to the inner carrier plate at thelocation within the concrete block. Rather, a metal anchor sleeve 75 isprovided having a cylindrical length which terminates at a first end 77where it is welded to the outwardly flaring anchor plate 71. The sleeve75 also has an opposite, second end 78. Once again, a metal end cap 79is used to join the anchor sleeve 75 at the second, distal end thereofto the inner carrier pipe 63 at a point along the length of piping whichis outside the concrete anchor block 73 and which is spaced apart fromthe location of the anchor plate. Again, this ensures that heat from thehigh temperature fluids in the piping is transferred to the end cap 79at a location along the length of piping which is distant from thelocation of the anchor plate 71.

The particular DDT piping system shown in FIG. 7 further includes alayer of polyurethane foam 70 surrounding conduit 69 and sleeve 75. Thepolyurethane foam layer is, in turn, surrounded by an HDPE jacket 72.The anchor plate 71 is further sealed by a heat shrink wrap 74 which isfusion bonded to the HDPE jacket on either side of the anchor plate. Theconventional components of the piping system shown in FIG. 5 arecommercially available from Thermacor Process, LP of Fort Worth, Tex.,assignee of the present invention, as the Duo-Therm 505 System™. Thepreviously described polyurethane and HDPE components used in such a DDTsystem are all conventional with the exception of the improved anchorplate and anchor sleeve arrangement of the invention which againtransfers any heat away from the anchor plate location to the locationof the end plate 79.

An invention has been provided with several advantages. The improvedanchor assembly of the invention provides an improved anchor point inpre-insulated piping systems of the type which are commerciallyavailable in the industry whether bonded foam or DDT systems. The anchorsystem of the invention is better able to accommodate the hightemperatures which are presently experienced at the location of thesteel anchor plate in existing anchor systems, where the anchor platecontacts the steel carrier pipe, particularly where the steel carrierpipe is carrying high temperature fluids. Because of the presence of thespecial anchor sleeve used in the assembly of the invention, theeffective heat transfer point between hot fluids in the carrier pipe andthe surrounding materials is moved down the length of pipe from thelocation of the anchor plate. As a result, less strain is placed uponthe conventional materials used to make up the anchor assembly. Bydecreasing the heat transfer at the location of the anchor point, it ispossible to increase the expected useful life of conventional corrosionprotective coatings. In fact, even when the outer jacket is breached andwater enters the system, conventional corrosion coatings may continue towork for longer periods of time where the anchor location is transformedto a “cool point.” The anchor system of the invention utilizes many ofthe conventionally available materials and manufacturing techniquescommonly used in the industry, and which is relatively simple in designand economical to implement.

While the invention has been shown in one of its forms, it is not thuslimited but is susceptible to various changes and modifications withoutdeparting from the spirit thereof.

What is claimed is:
 1. A drainable, dryable, testable pre-insulatedpiping system of the type used for conveying high temperature fluids,comprising: a length of insulated and jacketed pre-insulated piping, thelength of piping comprising an inner metal carrier pipe having aninterior surface and an exterior surface, an envelope of insulationsurrounding the inner metal carrier pipe exterior surface, and anintermediate metal conduit surrounding the envelope of insulation, theintermediate metal conduit also having an interior surface and anexterior surface, the length of piping having a joining end for joiningto an adjacent length of piping, whereby the adjacent lengths of pipingprovide a continuous length of fluid conduit for conveying hightemperature fluids; an anchor installation located at a selected pointalong the length of the piping system, the anchor installation includingan inner metal carrier pipe for joining to the joining end of anadjacent length of piping in the piping system, the inner metal carrierpipe being surrounded by an envelope of insulation, and wherein aspecial anchor sleeve surrounds at least a portion of the length of theinner metal carrier pipe and envelope of insulation, the anchor sleevehaving a cylindrical length which terminates at a first end at anoutwardly flaring anchor plate which is subsequently embedded within aconcrete anchor block, the anchor sleeve also having an opposite, secondend, the anchor sleeve being arranged to surround the envelope ofinsulation in spaced apart relationship to the inner metal carrier pipeso that the inner metal carrier pipe is separated from the intermediatemetal conduit by an air gap, the anchor sleeve extending outwardly fromthe concrete anchor block along the length of piping for a predetermineddistance, wherein the intermediate metal conduit and anchor sleeve are,in turn, surrounded by an envelop of foam insulation; an outerthermoplastic protective jacket surrounding the envelope of foaminsulation, the envelope of foam insulation being bonded to the exteriorsurface of the intermediate metal conduit and to the outer thermoplasticprotective jacket; and a metal end cap which joins the anchor sleeve atthe second end thereof to the inner metal carrier pipe at apredetermined point along the length of piping which is outside theconcrete anchor block and which is spaced apart from the location of theanchor plate, the predetermined point where the metal end cap joins theinner metal carrier pipe being selected so that heat from the hightemperature fluids in the piping is transferred to the metal end cap ata location along the length of piping which is outside the concreteanchor block and spaced away from the anchor plate, the end cap beingthe only point of metal contact between the anchor plate and itsassociated metal anchor sleeve and the inner metal carrier pipe.
 2. Thepre-insulated piping system of claim 1, wherein the envelope ofinsulation which surrounds the inner metal carrier pipe is selected fromthe group consisting of: high temperature rated mineral wool, foamglass, fiber-glass and calcium silicate.
 3. The pre-insulated pipingsystem of claim 2, wherein the intermediate metal conduit joins theanchor plate on a side thereof opposite the cylindrical anchor sleeve.4. The pre-insulated piping system of claim 1, wherein the envelope offoam insulation which surrounds the intermediate metal conduit ispolyurethane foam insulation.